Certain types of printers typically create a printed image by ejecting ink through orifices contained in an orifice plate onto an image receiving medium such as a print medium or a drum that transfers the image to the print medium. Repeated printing builds up contaminates, such as unused ink and debris from the print medium, in the orifices and on the orifice plate. To ensure a high quality printed image, the print head must be periodically cleaned of this contamination to provide an unhindered ink trajectory from the orifices.
A typical conventional cleaning sequence entails drawing ink and debris from the orifices onto the orifice plate and then wiping the orifice plate. One currently available printer, such as the printer shown in U.S. Pat. No. 5,184,147 to MacLane et at., includes a purge cap for drawing contamination from the orifices and a wiper mounted to the exterior of the purge cap for wiping the contamination from the orifice plate.
The purge cap and exterior wiper design of MacLane has several disadvantages: the purge cap and the exterior wiper each occupy a separate volume of space in the printer so that the printer design is not compact; time is required to move the orifice plate from the purge cap to the wiper so that the cleaning operation is slow; the purge cap cannot maintain a vacuum pressure on the orifice plate so that ink is not drawn from the orifices were the wiper to be used to wipe the orifice plate while under the vacuum; the wiper cannot be washed with clean ink ejected from the orifices because the purge cap will not catch the ink and so the utility of the cleaning operation is diminished unless the wiper is periodically manually cleaned; and the exteriorly mounted wiper is exposed to debris accumulating within the printer because the purge cap does not shield the wiper.
Accordingly, a need exists for a print head maintenance method and apparatus that clean a print head without the disadvantages of the prior art.